Design principles for enantiospecific para- and ortho-[3,3] rearrangements of chiral aryl-allyl ethers
Johanna Breinsperger1, Maximilian Kaiser1, Peter Gärtner1
1Institute of Applied Synthetic Chemistry, Technische Universität Wien Getreidemarkt 9/163 1060 Wien Austria maximilian.kaiser@tuwien.ac.at.
Abstract:
We report a systematic study that elucidates the regio-determining features of the stereoretentive para-Claisen-Cope and ortho-Claisen rearrangements of enantioenriched aryl-allyl ethers under mild catalytic conditions. The role of the aromatic substitution pattern as well as the nature of the rearranging ether moiety were thoroughly investigated, revealing that both para- and ortho-alkylation proceeded enantiospecifically with near-perfect chirality transfer. These findings resulted in rational design principles for accessing synthetically versatile, enantioenriched phenols and gave insights into how steric and electronic influences direct the [3,3]-rearrangements.
Related Concept Videos
[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
Prochirality
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
Naming Enantiomers
Regioselectivity and Stereochemistry of Hydroboration
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3


